Determination of As, Cr, and Cu concentrations in CCA-treated wood poles using acid decomposition in closed flasks, oven heating, and ICP-MS analysis

Abstract

To prevent the degradation of wood used for utility poles, a chromated copper arsenate (CCA) preservative is introduced to increase the wood's resistance to degradation. The components of CCA are highly toxic and may leach into the environment, contaminating the soil as well as surface and groundwater. The aim of the present study was to determine the As, Cr, and Cu concentration in samples of CCA-treated wood poles using acid decomposition in closed flasks, oven heating, and the ICP-MS technique. For this purpose, milled wood samples (particle size ≤425 μm) were decomposed in a mixture of concentrated HNO3 and H2O2 for 24 hours at 95 °C. The reference material NIST SRM 1575a Trace Elements in Pine Needles was used to evaluate the accu racy of the method, and the results obtained for As, Cr, and Cu were in agreement with the certified values. For the analysis of real samples, wood poles with different characteristics were used: poles submitted to impregnation under laboratory conditions, poles exposed to industrial treatment with preservatives, and poles removed from service. In the comparison of the results with those obtained for decomposition with microwave heating, the paired t-test showed no significant difference between the two methods. In addition, linear regression of the data yielded a high R value and the slope of the regression close to 1 for all of the elements, indicating that the proposed method is nearly identical with microwave heating for the determination of As, Cr, and Cu in wood pole samples.